There used to be a mine at this place, it was abandoned for many years. But 20 years ago there was a landslide here and this beautiful lake with water of unusual color appeared.
Nice shot. My daughter live near lots of old tin mines and the water that sits in the surrounding lakes also has interesting colours, but it contains finings (think that's what it is called0, anyway there are dangerous chemicals in it that cause the bright colours including arsenic, so be careful...
Ian